BERKELEY, CA (UroToday.com) - The assessment of tumor hypoxia with 18F-FMISO PET/CT in metastases of renal cell carcinoma provides some comprehension of the mechanism of action of sunitinib,
the antiangiogenic compound used in this prospective multicentric study. After one month of treatment, the decrease of tumor hypoxia measured by PET/CT implies that the long-term mechanism of action of sunitinib is an improvement of the functional value of tumor vasculature.
Our study did not schedule a very early assessment of tumor hypoxia, in the first days, or even in the first hours following the onset of sunitinib. Such an early 18F-FMISO PET/CT imaging could have shown a transient phase of increased hypoxia. Anyway, it is very likely that the long-term efficacy of sunitinib comes from a reduction of tumor hypoxia through a normalization of tumor vasculature as postulated by Jain.1
Further studies should asses the relationship between the decrease of tumor hypoxia and the evolution of perfusion parameters derived from CT or MRI dynamic acquisitions, such as tumor blood flow, tumor blood volume, and vascular permeabilityn.2 It might also be interesting to study the relationship between tumor hypoxia and plasma proangiogenic factors concentrations such as sVEGFR.
In our study, patients with initially hypoxic metastases had a shorter PFS than the others, a known fact for various types of other cancersn.3 Further studies with a greater number of patients might find an association between initial tumor hypoxia and overall survival.
- Jain RK. Normalization of tumor vasculature: an emerging concept in antiangiogenic therapy. Science 2005;307:58-62.
- Fournier LS, Oudard S, Thiam R, et al. Metastatic renal carcinoma: evaluation of antiangiogenic therapy with dynamic contrast-enhanced CT. Radiology;256:511-8.
- Vaupel P, Mayer A. Hypoxia in cancer: significance and impact on clinical outcome. Cancer Metastasis Rev 2007;26:225-39.
Florent Hugonnet as part of Beyond the Abstract on UroToday.com. This initiative offers a method of publishing for the professional urology community. Authors are given an opportunity to expand on the circumstances, limitations etc... of their research by referencing the published abstract.
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